Gene encoding PnFL-2 with TIFY and CCT motifs may control floral induction in Pharbitis nil

A PnFL-2 gene is a single copy gene that was isolated from the flower-induced cotyledons of Pharbitis nil. The deduced amino acid sequence of the PnFL-2 includes two functional domains, a single TIFY (ZIM) motif and nuclear localization signal CCT motif. The TIFY family is a novel plant specific gene involved in the regulation of diverse plant specific biological process, such as development and responses to phytochrome, implying that PnFL-2 may play a role in the mechanism of flowering induction. Subcelluar localization analysis confirmed that PnFL-2 is localized in the nucleus. Expression of PnFL-2 was induced during 16h-long inductive night, whereas accumulation of its transcripts significantly abolished by night-break, completely eliminated flowering induction of Pharbitis nil. Accumulation of its induced PnFL-2 transcripts depends on tissue, such as the cotyledons and the leaves. To study its biological functions directly, we have characterized gain of function transgenic over-expression plants for PnFL-2 in Arabidopsis. Transgenic plants that constitutively over-express PnFL-2 displayed slightly early flowering time under the long day condition as compare to those in wild type. These results indicate that PnFL-2 is potentially involved in the regulation of flowering induction in Pharbitis nil.